Natural ball and socket joints (such as hip (FIG. 1) and shoulder joints (FIG. 2)) allow for certain degrees of rotation along three independent axes. For instance, you can kick your leg forward/backward, outward/inward, and twist your leg. (The ball in that instance is the end of the femur that fits inside the enclosing socket of the hip.) Older adults and others in need of artificial ball and socket joints (such as hip and shoulder replacements) wish to maximize range of movement without a high risk of dislocation of the ball from the socket. Furthering this goal allows the prosthetic bearer to, among other things, participate maximally in fitness that can help prevent one's health from deteriorating, and also to avoid painful corrective surgeries that further disrupt the ball and socket connection and risk even further dislocation. Thus, there is an extremely substantial need for a prosthetic apparatus that allows for maximal range of rotational movement without dislocation.
There have been many attempts to constrain the ball to the socket in the past: For instance, U.S. Pat. Nos. 7,780,737; 7,766,971; 7,749,277; 7,335,231; 7,192,449; 7,179,298; 7,179,296; 7,169,186; 7,160,332; 7,144,427; 7,115,145; 7,074,24; 7,022,142; 6,986,792; 6,923,833; 6,527,808; 6,299,647; 6,042,612; 6,042,611; 5,916,270; 5,782,930; 5,639,280; 5,556,434; 5,092,897; 5,062,823; 4,960,427; 4,770,661; 3,996,625; U.S. Applications 20100174380; 20100087930; 20080125866; 20090088853 20070225818; 20070135927; 20070106392; 20070106389; 20060241780; 20060101; 20030050703; 20030191537; 20030212458; 20010032021. However, all are limited either in rate of dislocation or in range of smooth motion. Thus, this extremely substantial need for a prosthetic ball and socket apparatus that allows for maximal range of motion along each of the planes of rotation and along the line of twisting without dislocation has gone unmet for quite some time.